How do I unpack a signed long in big endian?

[aspangler]

I need something like

( $val ) = unpack( "N", $raw )

except that the number can be negative.

The code should be platform neutral.

Originally posted as a Categorized Question.

[Anonymous Monk]

$val = unpack( "N", $raw ^ "\x80\0\0\0" ) - ( 1 << 31 );